OPS335 NFS Lab

NFS RESOURCES

Online References:

• File Server Notes (Week 9 class notes)
• Linux NFS HOWTO
• NSF Security (List of tips regarding NSF and security)

OVERVIEW

In OPS235, you learned how to install and configure an SSH server to be able to use utilities such as ssh, scp and sftp. Although the sftp utility is useful for transferring files between different computers via the Internet, it is not considered useful or efficient for accessing files on servers that are connected over a local network.

Two popular protocols called Network File Server (NFS) and Samba (SMB) are used to provide high speed file access between servers on a local network. The NFS protocol allows a user to access files on another server in a local network in a similar way that local files on a same server are accessed. The Samba open-source software is used to access files from Windows servers using a combination of Windows protocols including NetBIOS, SMB, etc., and will be discussed in the next lab.

This lab will focus on installing, configuring and using NFS to access files between different Linux servers on your local network.

INVESTIGATION 1: USING AUTOMOUNT WITH NFS

In this investigation, we will set up an NFS server on our VM2 machine. We will then set up an NFS client on our VM3 machine so that we can view and import files of VM2's /home directory from our VM3 machine.

Prerequistites
Due to the changes made in lab3, you will now need your vm1 running (as the DNS server) in order for any of your virtual machines to be able to use the internet.

Setting up the NFS Server (VM2)

Perform the following tasks:

1. Make certain that all of your VMs are running.
2. Switch to your VM2 machine.
3. Although the NFS application was already installed on your VM, we will install additional utilities for NFS by issuing the following command:
   yum install nfs-utils
4. The /etc/exports file allows you to restrict the access to servers to access files for security purposes. Edit the /etc/exports file, and add the following line to the file:
   /home 192.168.x.4(rw,root_squash,insecure)
5. What does the IPADDR 192.168.x.4 represent? Record your answer in your lab logbook.
6. Issue the following command (in order of appearance) in order to start your NFS server:
   systemctl start rpcbind
   systemctl start nfs
7. Use the systemctl command to enable both the rpcbind and nfs services upon VM startup.
8. Issue the following command in order to add (or "build") the server's list of permitted exports:
   exportfs -r
9. Run and record the output of the following commands in your lab logbook:
   exportfs
   showmount -e
10. You will have to adjust your firewall settings on your VM2 machine to allow NFS to work (Tip: run the netstat command in order to determine the ports needed and issue the appropriate iptables command or commands). Make certain to save your current iptables rules so they remain unchanged whey you reboot your NFS server and your client VM.

Setting up & Testing the NFS Client (VM3)

Perform the following tasks:

1. make certain that your VM3 machine can connect to the network and that your VM1 machine is running as the DNS server (Tip: you can use the "host cbc.ca" command to see if DNS queries are being answered.
2. Make certain that you are logged into your VM3 machine.
3. Install the nfs-utils package on your VM3 machine.
4. Add the following line to the bottom of the /etc/fstab file on your VM3 machine:
   192.168.x.3:/home /home nfs4 defaults 0 0

Warning: Do not change any other lines in this file.
Do not change any lines in /etc/fstab file contained for your VM3 machine. Doing so can cause your VM3 machine not to boot properly.

5. Run the following command to confirm that SELinux will not block the network share:
   setsebool -P use_nfs_home_dirs 1
6. Issue the following command to mount any network shares without having to logout and login to your VM3:
   mount -a
7. Create an empty file within the regular user's home directory on your VM3 machine.
8. Issue the ls-l command for VM2 regular user's home directory. Do you see a file that you created there?
9. Switch to your VM2 machine and view the contents on your regular user's home directory. What you do you notice? What does this mean in terms of using NFS? Record your observations in your lab logbook.
10. Restart your VM3 machine and login with your regular user id.
11. Make certain that you iptables rules are the same to allow NFS to work
12. Check that the VM3 regular user's home directory is mounted by issuing the following command:
    mount | grep /home
13. If it is not, try running mount /home as root and observe any errors.
14. Create another file in the regular user's home directory on your VM3 machine.
15. Switch to your VM2 machine to see if you can view that file.
16. Finally, issue the ls-l command in your VM3 regular user's home directory to note the contents.

Record steps, commands, and your observations in INVESTIGATION 1 in your OPS335 lab log-book

INVESTIGATION 2: SETTING UP AUTO-MOUNT ON CLIENT (VM3)

In this investigation, we will be setting up to allow a network file share permanently on your VMs.

Perform the following tasks:

1. Switch to your VM3 machine.
2. Unmount the /home directory from VM2 by running umount /home
3. Comment or remove the line that you added in the /etc/fstab file in the previous investigation.
4. Restart your VM3 machine.
5. Install the autofs package by issuing the following command:
   yum install autofs
6. Rename the existing file /etc/auto.master file by issuing the following command:
   mv /etc/auto.master /etc/auto.master.orig
   Keep this file as a back-up in case you need to restore the file in the future.
7. Use the vi text editor to create a new (empty) /etc/auto.master file and add the following line:
   /home /etc/auto.home --timeout=60
8. Save your editing changes.
9. Use the vi text editor to create a file called /etc/auto.home and add add the following line:
   *   -fstype=nfs4,rw,nosuid,soft   192.168.x.3:/home/&
10. Save your editing changes.
11. Use the systemctl command to start the autofs service, and another systemctl command in order to ensure that the autofs service will automatically start at boot.
12. Log out of and back into vm3 using your regular user account (i.e. not root. You should be in your regular user account for both VM2 and VM3 machines).
13. Open a terminal and enter the following command:
    mount | grep home
14. How does it differ from the previous mount? Record your findings in your lab logbook.
15. On your VM3 machine, create another empty file with the name:
    touch yet_another_empty_file_from_vm3
16. Run and record the output of the following command (on both your VM2 and VM3 machines):
    df -hT
17. Switch to the nfs server (vm2), run and record the output of ls -l in your home directory (You should see the files you created on vm3).
18. Now that you have VM3 automatically mounting home directories from your VM2 machine, repeat the steps in this investigation in order to configure your VM1 machine to do the same.

Record steps, commands, and your observations in INVESTIGATION 2 in your OPS335 lab log-book

COMPLETING THE LAB

Arrange evidence (command output) for each of these items on your screen, then ask your instructor to review them and sign off on the lab's completion:

✓ Show mount information regarding vm3 and vm1 shares with NFS server (vm2)

✓ All files shown in network server (vm2)

✓ Display contents of /etc/exports, /etc/auto.master and /etc/auto.home files

✓ Lab logbook completed

EXPLORATION QUESTIONS

1. What does the no_root_squash option for an NFS mount mean?
2. Explain the meaning of the defaults option in an fstab entry. What do the numbers mean at the end?
3. What is the function of the 'exportfs' command?
4. What is the purpose of the 'showmount' command?
5. What is the meaning of the "timeout=60" phrase?
6. What is the meaning of the asterisk (*) in the file /etc/auto.home?
7. What is the meaning of the ampersand (&) in the file /etc/auto.home?
8. What is the role of the /etc/mtab file on the nfs server?
9. What port does nfs-server use?